A turbomachine, such as, for example, a single-shaft turbomachine, has a rotor with a shaft. What may be considered for mounting the shaft is, inter alia, a tilting-segment radial bearing in which the shaft can rotate about its axis. The tilting-segment radial bearing usually has three or four tilting segments, a distinction being made between lower and upper tilting segments. The lower tilting segments bear the weight of the shaft, its weight being diverted into a foundation via the lower tilting segments, the supporting ring and the bearing housing. The upper tilting segments, in the event of a fault, prevent the shaft from lifting off from the lower tilting segments and have a vibration-damping effect upon the shaft. The upper tilting segments either lie loosely on the shaft or are pressed onto the shaft by means of springs.
For lubrication and cooling, an oil flow is introduced through the tilting segments into the sealing gap between the shaft and the sliding surfaces of the tilting segments. When the shaft rotates, a hydrodynamic oil film, on which the shaft “floats”, is formed. If imbalances occur during rotation, vibrations may arise. If the upper tilting segments lie loosely on the shaft, only slight vibration damping can emanate from them. Conventionally, for vibration damping, the upper tilting segments are pressed onto the shaft by means of springs. When the machine is shut down, the shaft has to be rotated slowly in what is known as a turn mode, so that it does not sag during cooling. In this turn mode and when the machine is started up, however, there is the disadvantage that the upper tilting segments press onto the shaft, since this may cause damage to the sliding surfaces of the tilting segments and to the surface of the shaft.
Furthermore, there can only be a small quantity of oil flowing into the sealing gap, and therefore only insignificant cooling occurs. Moreover, because of the poor sliding behavior in the turn mode, high drive forces are required, with the result that the efficiency of the machine decreases.
FR 2574503 A1 describes a hydrodynamic bearing in which a fluid connected to a pressure chamber is located in the gap between a shaft and a tilting segment, the pressure chamber exerting pressure upon the tilting segment. Further bearings are described in U.S. Pat. No. 3,497,276 A and DE 14 25 111 A1.